How to Make High Resolution Images on Your Computer or Smartphone

Increase the resolution of any photo on your PC, Mac, or mobile device

Taking a digital image and making it smaller is a relatively simple task. Knowing how to increase the resolution of an image is a little more challenging. Here's how to make an image a higher resolution and improve the quality of a blown-up photo.

This article provides instructions for desktop GIMP 2.10, which is available for Windows, macOS, and Linux. It also includes instructions for macOS X Preview (macOS 10.3 or later) and Image Save, which requires iOS 9.0 or later.

Principles of Making a Picture Higher Resolution

Resolution correlates to the number of pixels in a digital photograph or image. The more pixels there are, the higher the image's resolution.

To improve a picture's resolution, increase its size, then make sure it has the optimal pixel density. The result is a larger image, but it may look less sharp than the original picture. The bigger you make an image, the more you'll see a difference in sharpness. This process makes the picture larger and adds pixels, not more detail.

As a rule of thumb, 300 pixels-per-inch is the accepted standard for printed images.

To mitigate the loss of sharpness, follow these tips:

  • Avoid a significant increase in size: All images are different. When you increase the dimensions by more than 30 percent or 40 percent, you'll likely notice a loss of sharpness.
  • Use sharpen tools when available: GIMP and Photoshop include features for sharpening images. However, not all apps have these tools. The final effect can seem unnatural, so use sharpen tools sparingly to retain a similar look to the original picture.

How to Make High-Resolution Images using Desktop GIMP

GIMP is a free, open-source image editing tool available for Windows, macOS, and Linux. It offers broad support for a host of image formats, making it ideal for this kind of task.

Here's how to improve image resolution with GIMP:

  1. Open GIMP.

  2. Select File > Open.

    File > Open menu in Gimp for macOS
  3. In the Open Image dialog box, choose the image and select Open.

    Open dialog box in Gimp for macOS
  4. Make sure the image window is the active window.

  5. Press Ctrl+A (Windows) or Command+A (Mac) to select the whole image.

  6. Press Ctrl+C or Command+C to copy the image.

  7. To create a higher resolution copy, select File > New to open the Create a New Image dialog box.

    File > New menu items in Gimp for macOS
  8. To ensure the final picture has a resolution of 300 pixels-per-inch, select Advanced Options.

    Advanced options in Gimp for macOS

    The pre-filled width and height match the current image. Don't change these values.

  9. The dialog box expands, revealing the X and Y resolutions for the image. The boxes may show the canvas is set to 300. If it is not, adjust the X and Y values to 300, then select OK.

    X and Y resolution fields in Gimp for macOS
  10. You now have a new image window which has the same dimensions as the original photo.

  11. Select the window for the new image, then select Image > Canvas Size.

    File > Canvas Size menu item in Gimp for macOS
  12. The Set Image Canvas Size dialog box opens. This is where you'll adjust the canvas size.

  13. Before you adjust the canvas width or height, make sure that the chain icon to the right of both measurements is locked.

    Chain link icon in Gimp for macOS
  14. Enter the new image width, then press Tab. The height automatically adjusts to match the image scale. This example goes from just over 4000 pixels to 6000 pixels.

    Be sure to remember or jot down your new dimensions. You'll need these again later.

  15. Select Resize.

    Resize button in Gimp for macOS
  16. In the new image window, press Ctrl+V or Command+V to paste the image.

    Image pasted to new image window in Gimp.
  17. Drag the corner of the image window (and zoom out if necessary) to see all corners of the resized canvas. The image is pasted in the center of the new image window at its original size.

    Pasted image zoomed out in Gimp.
  18. To make the pasted image fully cover the new canvas size, go to the Layers dialog and select Floating Selection (Pasted Layer) if it isn't selected.

    Pasted Layer in Gimp for macOS
  19. Go to the Toolbox dialog and select the Scale tool.

    Scale tool in Gimp for macOS
  20. Select the pasted image. A scale guide and the Scale dialog box appear. In the Scale dialog box, ensure the chain icon is locked, then enter the same width value you used in step 13.

    Chain icon in scale dialog for Gimp in macOS
  21. You'll see a preview of what the resized image will look like. If it looks good, select Scale.

    Scale button in Gimp for macOS
  22. The image is resampled at the newer size.

    Gimp resampled image.
  23. Before exporting the image, check the quality of it by zooming in. To do this, select View > Zoom, then choose a zoom level.

    Zoom menu in Gimp for macOS
  24. When you're happy with the result, go to the Layers dialog, right-click Floating Selection (Pasted Layer), then select Anchor Layer to lock it to the background.

    Anchor Layer in Gimp for macOS
  25. To export your image, select File > Export.

    Export menu in Gimp for macOS
  26. This opens the Export Image dialog box. Choose where you want to save the resized image and name it. Then select Export.

    File name field in Save dialog in Gimp for macOS

    When naming an image, you can also set the file type by typing the extension. For example, call the image new_photo.png to save it as a PNG file, or name it new_photo.jpg to save it as a JPEG.

  27. The Export Image as dialog box appears, offering settings for the saved photo. To get the best image quality, move the Compression Level slider to zero, then select Export.

    Compression level slider in Gimp for macOS

How to Increase the Resolution of an Image using macOS X Preview

Preview is a useful tool for viewing photos and PDFs on your Mac, and it includes some handy image editing tools.

  1. Locate the image file, then right-click it and select Open with > Preview.

    Open with Preview on macOS
  2. Select the Markup Toolbar icon.

    Markup toolbar in Preview on macOS
  3. Select the Adjust Size icon.

    Adjust Size icon in Preview on macOS
  4. Adjust the width to the desired amount, then select OK. This example resizes a picture from a width of 1000 pixels to 1300 pixels.

    Width and Height fields in Preview on macOS

    Ensure the lock icon is closed and Resample Image is selected.

  5. The image resizes. Select File > Save to overwrite the original image or File > Export to save it as a new file.

    File > Save and File > Export menu items in Preview on macOS

How to Increase the Resolution of an Image using Image Size for iPhone

Image Size for iOS is a photo editing tool that also lets you resize images. It's free, but you can choose to pay if you want to remove ads.

  1. Install and open Image Size.

  2. Tap the main white box. Select OK to grant the app access to your photos, then select the white box once more to open the image picker.

  3. Select the image you want to resize.

    Choosing a photo in Image Size
  4. Select Choose to open the image.

  5. Select the chain icon to lock the Width and Height values.

  6. Set your desired Width value, then select Done. This example scales the image up to 6000 pixels. The Height value automatically adjusts as well.

    Importing an image
  7. The photo resamples at the new size. You can pinch and zoom to check the pixel quality.

  8. Select the gear icon to view additional options. Ensure the Output Quality slider is at 100 percent.

    Settings Gear, Print size correction factor buttons on iOS
  9. If you intend to print the image, smooth out the pixelation. To do this, select the + icon to increase the Print size correction factor, then select the back arrow to return to the main page.

  10. To save the final image, select the save arrow.

    Save arrow and output message on iOS